Photoelectric conversion apparatus, focus detection apparatus, and image pickup system

ABSTRACT

A photoelectric conversion apparatus includes a first line sensor unit in which a plurality of pixels are arranged in a first direction, a second line sensor unit in which a plurality of pixels are arranged in a second direction, and a third line sensor unit in which a plurality of pixels are arranged in a third direction. Each of the pixels includes a photoelectric conversion portion and a transistor. The second direction is perpendicular to the first direction and the third direction is not perpendicular to the first and the second directions. A channel of the transistor is provided in the first direction or the second direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One disclosed aspect of the embodiments relates to a photoelectricconversion apparatus, a focus detection apparatus, and an image pickupsystem.

2. Description of the Related Art

It is known that an image pickup apparatus such as a digital camera anda digital video camera includes a focus detection apparatus. JapanesePatent Laid-Open No. 2011-100077 describes a focus detection apparatusincluding a photoelectric conversion apparatus having focus detectionregions in a vertical direction, a horizontal direction, and a diagonaldirection with respect to an image pickup area of an image pickupsensor. However, in Japanese Patent Laid-Open No. 2011-100077, adetailed structure of the photoelectric conversion apparatus is notsufficiently discussed, so that there is a risk that a focal pointcannot be accurately detected.

SUMMARY OF THE INVENTION

One disclosed aspect of the embodiments provides a photoelectricconversion apparatus including a first line sensor unit in which aplurality of pixels are arranged in a first direction, a second linesensor unit in which a plurality of pixels are arranged in a seconddirection, and a third line sensor unit in which a plurality of pixelsare arranged in a third direction. Each of the pixels includes aphotoelectric conversion portion and a transistor. The second directionis perpendicular to the first direction and the third direction is notperpendicular to the first and the second directions. A channel of thetransistor is provided in the first direction or the second direction.

Further features of the disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of an image pickup apparatusaccording to a first embodiment.

FIG. 2 is a schematic perspective view showing a configuration of afocus detection apparatus according to the first embodiment.

FIG. 3 is a schematic plan view showing a multi-hole aperture of thefocus detection apparatus according to the first embodiment.

FIGS. 4A, 4B, 4C, 4D, and 4E are schematic plan views showing a focusdetection sensor according to the first embodiment.

FIGS. 5A, 5B, 5C, and 5D are diagrams showing a configuration of pixelsin the focus detection sensor according to the first embodiment.

FIG. 6 is an equivalent circuit diagram of a pixel of a focus detectionsensor according to a second embodiment.

FIG. 7 is a diagram showing a configuration of a maximum value andminimum value detector of the focus detection sensor according to thesecond embodiment.

FIG. 8 is a diagram showing a configuration of a PB comparator of thefocus detection sensor according to the second embodiment.

FIG. 9 is a schematic plan view showing a sensor cell portion of thefocus detection sensor according to the second embodiment.

FIG. 10A is a schematic plan view showing the sensor cell portion of thefocus detection sensor according to the second embodiment. FIGS. 10B and10C are cross-sectional views showing the sensor cell portion of thefocus detection sensor according to the second embodiment.

FIG. 11 is a schematic plan view showing the sensor cell portion of thefocus detection sensor according to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Embodiments will be described with reference to the drawings.

First Embodiment

As shown in FIG. 1, an image pickup apparatus 1 includes an image pickuplens 10 and a camera main body. The camera main body is configured sothat the image pickup lens may be attached and removed through a mountportion not shown in FIG. 1. The image pickup apparatus 1 is, forexample, a single lens reflex camera.

The image pickup lens 10 is a replaceable image pickup lens for formingan image of an object on an image pickup device. The image pickup lens10 includes an image pickup optical system including a focus adjustmentlens not shown in FIG. 1. The focus (state) of the image pickup lens 10is adjusted by a control unit 80 described later according to a resultof a focus detection process performed by a focus detection apparatus100 described later. The image pickup lens 10 is held by a lens barrelLB so that the image pickup lens 10 may be moved in an optical axis OAdirection. Although the image pickup lens 10 is not a component of theimage pickup apparatus 1 when the image pickup lens 10 is removed fromthe camera main body, the image pickup lens 10 is required to beattached to the camera main body when the focus detection apparatus 100performs focus detection, so that the image pickup lens 10 is treated asa component of the image pickup apparatus 1.

The camera main body includes a main mirror 20, a finder optical system30, a sub-mirror 40, an image pickup device 50, the focus detectionapparatus 100, and the control unit 80.

The main mirror 20 is formed by a partially-transmissive half mirror ora movable mirror on a part of which a half mirror surface is included.The main mirror 20 reflects a part of light passing through the imagepickup lens 10 and guides the reflected light along an optical axis OA″to the finder optical system 30 described later. On the other hand, themain mirror 20 lets a part of the light passing through the image pickuplens 10 pass through and guides the passing light along an optical axisOA to the sub-mirror 40 described later.

The finder optical system 30 is an optical system for observing anobject, the image of which is captured. In other words, the finderoptical system 30 artificially provides an observation image equivalentto the image of the object, the image of which is captured, to a user.As shown in FIG. 1, the finder optical system 30 includes a focusingplate 32, a pentaprism 34, and an eye lens 36.

The light from the image pickup lens 10, which is reflected by the mainmirror 20, is collected near the focusing plate 32. The focusing plate32 diffuses object light and emits the diffused object light to thepentaprism 34. The pentaprism 34 is an optical path conversion device.The pentaprism 34 reflects the light diffused by the focusing plate 32by a plurality of surfaces and guides the light to the eye lens 36. Theeye lens 36 is configured so that a user may observe a finder's field ofview formed on the focusing plate 32 through the eye lens 36.

The sub-mirror 40 is disposed on a downstream side of the optical axisOA with respect to the main mirror 20. The sub-mirror 40 reflects thelight (transmitted light) passing through the main mirror 20 and guidesthe reflected light to the focus detection apparatus 100 along theoptical axis OA′. The optical axis OA′ is an optical axis deflected fromthe optical axis OA by the sub-mirror 40. The sub-mirror 40 isconfigured to be able to be inserted into or removed from an imagepickup optical path (optical axis OA). The sub-mirror 40 is disposedinto a predetermined position on the image pickup optical path (opticalaxis OA) when an object is observed from the finder and is removed fromthe image pickup optical path (optical axis OA) when an image of theobject is captured.

The image pickup device 50 includes a pixel array in which a pluralityof pixels are regularly arranged. Typically, the pixels are arranged ina matrix pattern. The image pickup device 50 converts an image of theobject, which is formed on an image pickup area (pixel array) by theimage pickup lens 10, into an image signal. For example, the imagepickup device 50 is formed by an area (two-dimensional) sensor, whichphotoelectrically converts received light for each pixel and accumulatesan electrical charge according to received light quantity for eachpixel, and from which the electrical charges are read. The image pickupdevice 50 may be formed by, for example, a CMOS image sensor or a CCDimage sensor. A predetermined process is performed on an output signalfrom the image pickup device 50 by an image processing circuit not shownin FIG. 1. Thereby the output signal becomes image data and the imagedata is converted into image data to be recorded. Thereafter, the imagedata to be recorded is recorded in a recording medium such as asemiconductor memory, an optical disk, and a magnetic tape which are notshown in FIG. 1.

The focus detection apparatus 100 detects a focus state of the imagepickup lens 10 by using a phase difference method. In other words, thefocus detection apparatus 100 divides the light which passes through theimage pickup lens 10 and is reflected by the sub-mirror 40 and detectsthe focus state of the image pickup lens 10 according to a positionalrelationship between a plurality of images formed by divided lightfluxes. Specifically, the focus detection apparatus 100 forms aplurality of pairs of images and detects the focus state of the imagepickup lens 10 according to a signal obtained by photoelectricallyconverting each pair of images.

The focus detection apparatus 100 will be more specifically described.As shown in FIG. 2, the focus detection apparatus 100 includes a fieldof view mask 110, a field lens 111, a filter 113, a multi-hole aperture114, a re-imaging lens unit (secondary optical system) 115, and a focusdetection sensor 116 along the optical axis OA′ in this order.

The field of view mask 110 includes a rectangular opening 110 a forlimiting a light flux passing through the image pickup lens 10 in thecentral portion thereof. The field of view mask 110 is disposed near apredetermined image plane of the image pickup lens 10.

The field lens 111 is disposed on the downstream side of the opticalaxis OA′ with respect to the field of view mask 110. The field lens 111includes a lens member 111 a having an optical effect. The lens member111 a is a portion corresponding to the opening 110 a of the field ofview mask 110 in the field lens 111.

The filter 113 blocks light having a wavelength longer than that of nearinfrared light. The filter 113 is applied to detect the focal point ofthe image pickup lens 10 aberration-corrected with respect to visiblelight and prevent unnecessary infrared light from entering the focusdetection sensor 116.

The multi-hole aperture 114 is formed of a thin film and disposedadjacent to the filter 113 on the downstream side of the optical axisOA′. The multi-hole aperture 114 includes an opening 114 a and theopening 114 a includes openings 114 av 1, 114 av 2, 114 ah 1, 114 ah 2,114 as 1, 114 as 2, 114 ad 1, and 114 ad 2. As shown in FIG. 3, themulti-hole aperture 114 includes a pair of openings 114 av 1 and 114 av2 arranged in the longitudinal direction (Y direction) of the opening110 a and a pair of openings 114 ah 1 and 114 ah 2 arranged in the shortdirection (X direction) of the opening 110 a. Further, the multi-holeaperture 114 includes a pair of openings 114 as 1 and 114 as 2 arrangedin a left-up 45 degrees diagonal direction and a pair of openings 114 ad1 and 114 ad 2 arranged in a right-up 45 degrees diagonal direction inthe central portion thereof.

The re-imaging lens unit 115 includes a first focus detection opticalsystem FD1 and a second focus detection optical system FD2. The firstfocus detection optical system FD1 divides the light flux limited by theopening 110 a of the field of view mask 110 in at least one direction ofthe longitudinal direction (Y direction) and the short direction (Xdirection) of the opening 110 a. The second focus detection opticalsystem FD2 divides the light flux limited by the opening 110 a of thefield of view mask 110 in a diagonal direction making an acute angle(for example, 45 degrees) with the longitudinal direction of the opening110 a in a plane perpendicular to the optical axis of the light flux.The re-imaging lens unit 115 forms a re-imaged image (secondary image)of the object image on the predetermined image plane formed by the imagepickup lens 10 on each device array in a plurality of pairs of devicearrays of the focus detection sensor 116 disposed on the downstream sideof the optical axis OA′. In each device array in each pair of the devicearrays, as described later, a plurality of focus detection devices arearranged in a predetermined direction. The re-imaging lens unit 115includes prism portions and lens portions corresponding to the fourpairs of openings included in the multi-hole aperture 114.

Next, a focus detection operation of the focus detection apparatus 100will be described. Here, suffixes 1 and 2 of the reference numerals inFIG. 3 represent a pair of elements that form a pair of object images ina focus detection apparatus using a phase difference method.

The openings 114 av 1, 114 av 2, 114 ah 1, and 114 ah 2 of themulti-hole aperture 114 are arranged to be inscribed in substantiallythe same circle. The openings 114 as 1, 114 as 2, 114 ad 1, and 114 ad 2of the multi-hole aperture 114 are arranged to be inscribed insubstantially the same circle which has the same center as that of theabove inscribed circle and has a diameter larger than that of the aboveinscribed circle. By arranging the openings as described above, thelight flux of the image pickup lens 10 brighter (having an F numbersmaller) than that which reaches the openings 114 av 1, 114 av 2, 114 ah1, and 114 ah 2 reaches the openings 114 as 1, 114 as 2, 114 ad 1, and114 ad 2.

Next, the light flux passing through the opening 110 a of the field ofview mask 110 (the light flux limited by the opening 110 a) is guided tothe prism portion and the lens portion included in the re-imaging lensunit 115 located on the downstream side of the optical axis OA′ withrespect to the multi-hole aperture 114. The opening 110 a of the focusdetection apparatus 100 is provided for the focus detection opticalsystem including the lens member 111 a of the field lens 111, theopening 114 a of the multi-hole aperture 114, and the prism portion 1151a and the lens portion 1152 a of the re-imaging lens unit 115.

The light flux emitted from the re-imaging lens unit 115 enters thefocus detection sensor 116 located on the downstream side of the opticalaxis OA′. Four pairs of secondary images (that is, eight secondaryimages) of an object image (optical image) of the opening 110 a of thefield of view mask 110 are formed on the focus detection sensor 116.

FIG. 4A a schematic plan view showing the focus detection sensor 116 onwhich the object images are formed. In FIG. 4A, reference numerals 117av 1 to 117 ad 2 denote the optical images formed by the opening 110 aof the field of view mask 110 when the image pickup lens 10 is focused.Two optical images corresponding to one opening of the field of viewmask 110 are formed by a function of a pair of openings (correspondingto suffixes 1 and 2) of the multi-hole aperture 114 and a pair of theprism portion and the lens portion of the re-imaging lens unit 115.

A pair of light fluxes divided in the longitudinal direction (Ydirection) of the opening 11 a by the first focus detection opticalsystem FD1 form a pair of optical images 117 av 1 and 117 av 2. A pairof light fluxes divided in the short direction (X direction) of theopening 11 a by the first focus detection optical system FD1 form a pairof optical images 117 ah 1 and 117 ah 2. A pair of light fluxes dividedin a left-up 45 degrees diagonal direction by the second focus detectionoptical system FD2 form a pair of optical images 117 as1 and 117 as2. Apair of light fluxes divided in a right-up 45 degrees diagonal directionby the second focus detection optical system FD2 form a pair of opticalimages 117 ad 1 and 117 ad 2.

A pair of device arrays 116 av 1 and 116 av 2 are arranged inside thepair of optical images 117 av 1 and 117 av 2. In the pair of devicearrays 116 av 1 and 116 av 2, six pairs of focus detection devices 116av 1-1 to 116 av 1-6 and 116 av 2-1 to 116 av 2-6 extending in thelongitudinal direction (Y direction) of the opening 110 a are arranged.Here, the focus detection devices having the same number after thehyphen form a pair. In each device array of the pair of device arrays116 av 1 and 116 av 2, a plurality of focus detection devices arearranged in the short direction (X direction) of the opening 110 a.Thereby, it is possible to define a plurality of third focus detectionareas which are arranged in the short direction (X direction) of theopening 110 a and which extend in the longitudinal direction (Ydirection) of the opening 110 a in a picture plane on the predeterminedimage plane of the image pickup lens 10.

Similarly, a pair of device arrays 116 ah 1 and 116 ah 2 are arrangedinside the pair of optical images 117 ah 1 and 117 ah 2. In the pair ofdevice arrays 116 ah 1 and 116 ah 2, ten pairs of focus detectiondevices 116 ah 1-1 to 116 ah 1-10 and 116 ah 2-1 to 116 ah 2-10extending in the short direction of the opening 110 a are arranged.Here, the focus detection devices having the same number after thehyphen form a pair. In each device array of the pair of device arrays116 ah 1 and 116 ah 2, a plurality of focus detection devices arearranged in the longitudinal direction of the opening 110 a. Thereby, itis possible to define a plurality of fourth focus detection areas whichare arranged in the longitudinal direction of the opening 110 a andwhich extend in the short direction of the opening 110 a in the pictureplane on the predetermined image plane of the image pickup lens 10.

As a result, the focus detection sensor 116 includes a plurality offirst focus detection devices 116 av 1-1 to 116 av 1-6, 116 av 2-1 to116 av 2-6, 116 ah 1-1 to 116 ah 1-10, and 116 ah 2-1 to 116 ah 2-10shown in FIGS. 4B and 4C. The plurality of first focus detection devicesreceive the light fluxes divided by the first focus detection opticalsystem FD1. Each first focus detection device photoelectrically convertsthe received light to generate a signal (electrical charge) fordetecting a focal point. Each first focus detection device is, forexample, a photodiode. The plurality of first focus detection devicesdefine a plurality of first focus detection regions which extend indivision directions of the first focus detection optical system FD1 inthe picture plane on the predetermined image plane of the image pickuplens and which are arranged at predetermined arrangement intervals. Theplurality of first focus detection regions include the plurality ofthird focus detection areas and the plurality of fourth focus detectionareas. Thereby, it is possible to define a plurality of focus detectionregions (focus detection areas) extending in approximate latticedirections on the predetermined image plane of the image pickup lens 10.Therefore, it is easy to improve a processing accuracy of focusdetection without depending on a (direction of) spatial pattern of theobject.

Similarly, a pair of device arrays 116 as1 and 116 as2 are arrangedinside a pair of optical images 117 as1 and 117 as2. In the pair ofdevice arrays 116 as1 and 116 as2, ten pairs of focus detection devices116 as1-1 to 116 as1-10 and 116 as2-1 to 116 as2-10 extending in aleft-up 45 degrees diagonal direction are arranged. Here, the focusdetection devices having the same number after the hyphen form a pair.In each device array of the pair of device arrays 116 as1 and 116 as2, aplurality of focus detection devices are arranged in the longitudinaldirection of the opening 110 a. Thereby, it is possible to define aplurality of first focus detection areas 115 as-1 to 115 as-10 which arearranged in the longitudinal direction of the opening 110 a and whichextend in the left-up 45 degrees diagonal direction in the picture planeon the predetermined image plane of the image pickup lens 10.

Similarly, a pair of device arrays 116 ad 1 and 116 ad 2 are arrangedinside a pair of optical images 117 ad 1 and 117 ad 2. In the pair ofdevice arrays 116 ad 1 and 116 ad 2, ten pairs of focus detectiondevices 116 ad 1-1 to 116 ad 1-10 and 116 ad 2-1 to 116 ad 2-10extending in a right-up 45 degrees diagonal direction are arranged.Here, the focus detection devices having the same number after thehyphen form a pair. In each device array of the pair of device arrays116 ad 1 and 116 ad 2, a plurality of focus detection devices arearranged in the longitudinal direction of the opening 110 a. Thereby, itis possible to define a plurality of second focus detection areas 115ad-1 to 115 ad-10 which are arranged in the longitudinal direction ofthe opening 110 a and which extend in the right-up 45 degrees diagonaldirection in the picture plane on the predetermined image plane of theimage pickup lens 10.

As a result, the focus detection sensor 116 includes a plurality ofsecond focus detection devices 116 as1-1 to 116 as1-10, 116 as2-1 to 116as2-10, 116 ad 1-1 to 116 ad 1-10, and 116 ad 2-1 to 116 ad 2-10 shownin FIGS. 4D and 4E. The plurality of second focus detection devicesreceive the light fluxes divided by the second focus detection opticalsystem FD2. Each second focus detection device photoelectricallyconverts the received light to generate a signal (electrical charge) fordetecting a focal point. Each second focus detection device is, forexample, a photodiode. The plurality of second focus detection devicesdefine a plurality of second focus detection areas which extend indivision directions of the second focus detection optical system FD2 inthe picture plane on the predetermined image plane of the image pickuplens. The plurality of second focus detection regions include theplurality of first focus detection areas 115 as-1 to 115 as-10 and theplurality of second focus detection areas 115 ad-1 to 115 ad-10.Thereby, it is possible to define a plurality of focus detection regions(focus detection areas) which extend in the left-up 45 degrees diagonaldirection and the right-up 45 degrees diagonal direction so as to crosseach other and which are arranged in the longitudinal direction of theopening 110 a. Therefore, it is easy to improve a processing accuracy offocus detection without depending on a (direction of) spatial pattern ofthe object by using the focus detection regions along with theaforementioned focus detection regions extending in approximate latticedirections.

When the image pickup device 50 has a plurality of pixels arranged in amatrix form, if the rows and columns of the matrix are assumed to be inparallel with a first direction and a second direction respectively, thesecond focus detection devices 116 as1-1 to 116 as1-10, 116 as2-1 to 116as2-10, 116 ad 1-1, to, 116 ad 1-10, and 116 ad 2-1, to 116 ad 2-10 arearranged in diagonal directions with respect to the matrix of the imagepickup device.

Next, a detailed configuration of the focus detection sensor accordingto the present embodiment will be described. The photoelectricconversion apparatus used as the focus detection sensor is assumed to bean apparatus in which a plurality of focus detection devices are formedon a semiconductor substrate.

FIG. 5A shows one of the first focus detection devices 116 av 1-1 to 116av 1-6 and 116 av 2-1 to 116 av 2-6 as a typical example. Here, thefirst focus detection devices are collectively referred to as a focusdetection device 116 av as a first line sensor unit.

The focus detection device 116 av includes five pixels pav1 to pav5. Thepixels pav1 to pav5 include photodiodes 1160 av-1 to 1160 av-5 and MOStransistors 201 to 205 and 206 to 210 respectively. The MOS transistors201 to 210 are provided to amplify a signal based on electrical chargegenerated from the photodiodes 1160 av-1 to 1160 av-5 and transfer theelectrical charge when the MOS transistors have an electrical chargetransfer structure. The MOS transistors 201 to 210 are exemplarilyshown. In FIG. 5A, reference numeral 2011 denotes the gate of the MOStransistor 201 and reference numeral 2012 denotes the main electroderegion of the MOS transistor 201. The focus detection device 116 av 1 isdisposed away from the focus detection device 116 av 2 used as a fourthline sensor unit and makes a pair with the focus detection device 116 av2. The pixels included in the focus detection device 116 av 2 arearranged along the first direction.

In the focus detection device 116 av, the pixels pav1 to pav5 arearranged along the Y direction. The channels of the MOS transistors 201to 205 are provided in the X direction in FIG. 5A. Here, “the channel ofthe transistor is provided in the X direction” means a configuration inwhich a channel region formed below the gate when the transistor isturned on causes a source region and a drain region located in the Xdirection to be electrically connected to each other. On the other hand,the channels of the MOS transistors 206 to 210 are provided in the Ydirection. In other words, when the Y direction is defined as the firstdirection and the X direction is defined as the second direction, thepixels pav1 to pav5 are arranged in the first direction and the channelsof the transistors included in the pixels pav1 to pav5 are provided inthe first or the second direction.

Here, the direction in which the channel of the transistor is providedmay be rephrased as a direction in which a current flows between thesource and the drain when the transistor is conductive. The directionmay be further rephrased as a direction in which a gate electrode thatcontrols conduction between the source and the drain which form parts ofthe transistor respectively orthogonally intersects a side in contactwith the source and the drain when the transistor is seen from above.

Next, FIG. 5B shows one of the focus detection devices 116 ah 1-1 to 116ah 1-10 and 116 ah 2-1 to 116 ah 2-10 as a typical example. Here, thefocus detection devices are collectively referred to as a focusdetection device 116 ah as a second line sensor unit.

The focus detection device 116 ah includes five pixels pah1 to pah5. Thepixels pah1 to pah5 include photodiodes 1160 ah-1 to 1160 ah-5 and MOStransistors 211 to 215 and 216 to 220 respectively. The MOS transistors211 to 220 are provided to amplify a signal based on electrical chargegenerated from the photodiodes 1160 ah-1 to 1160 ah-5 and transfer theelectrical charge when the MOS transistors have an electrical chargetransfer structure. The MOS transistors 211 to 220 are exemplarilyshown. In FIG. 5B, reference numeral 2013 denotes the gate of the MOStransistor 211 and reference numeral 2014 denotes the main electroderegion of the MOS transistor 211. The focus detection device 116 ah 1 isdisposed away from the focus detection device 116 ah 2 used as a fifthline sensor unit and makes a pair with the focus detection device 116 ah2. The pixels included in the focus detection device 116 ah 2 arearranged along the second direction.

In the focus detection device 116 ah, the pixels pah1 to pah5 arearranged along the X direction. The channels of the MOS transistors 211to 215 are provided in the Y direction in FIG. 5B. Here, “the channel ofthe transistor is provided in the Y direction” means a configuration inwhich a channel region formed below the gate when the transistor isturned on causes a source region and a drain region located in the Ydirection to be electrically connected to each other. On the other hand,the channels of the MOS transistors 216 to 220 are provided in the Xdirection. In other words, when the Y direction is defined as the firstdirection and the X direction is defined as the second direction, thepixels pah1 to pah5 are arranged in the second direction and thechannels of the transistors included in the pixels pah1 to pah5 areprovided in the first or the second direction.

Next, FIG. 5C shows one of the focus detection devices 116 as1-1 to 116as1-10 and 116 as2-1 to 116 as2-10 as a typical example. Here, the focusdetection devices are collectively referred to as a focus detectiondevice 116 as as a third line sensor unit.

The focus detection device 116 as includes five pixels pas1 to pas5. Thepixels pas1 to pas5 include photodiodes 1160 as-1 to 1160 as-5 and MOStransistors 221 to 225 and 226 to 230 respectively. The MOS transistors221 to 230 are provided to amplify a signal based on electrical chargegenerated from the photodiodes 1160 as-1 to 1160 as-5 and transfer theelectrical charge when the MOS transistors have an electrical chargetransfer structure. The MOS transistors 221 to 230 are exemplarilyshown. In FIG. 5C, reference numeral 2015 denotes the gate of the MOStransistor 221 and reference numeral 2016 denotes the main electroderegion of the MOS transistor 221. The focus detection device 116 as1 isdisposed away from the focus detection device 116 as2 used as a sixthline sensor unit and makes a pair with the focus detection device 116as2. The pixels included in the focus detection device 116 as2 arearranged along a third direction.

In the focus detection device 116 as, the pixels pas1 to pas5 arearranged along an S direction. The channels of the MOS transistors 221to 225 are provided in the Y direction in FIG. 5C. Here, “the channel ofthe transistor is provided in the Y direction” means a configuration inwhich a channel region formed below the gate when the transistor isturned on causes a source region and a drain region located in the Ydirection to be electrically connected to each other. On the other hand,the channels of the MOS transistors 226 to 230 are provided in the Xdirection. In other words, when the Y direction is defined as the firstdirection, the X direction is defined as the second direction, and the Sdirection is defined as the third direction, the pixels pas1 to pas5 arearranged in the third direction and the channels of the transistorsincluded in the pixels pas1 to pas5 are provided in the first or thesecond direction.

Next, FIG. 5D shows one of the focus detection devices 116 ad 1-1 to 116ad 1-10 and 116 ad 2-1 to 116 ad 2-10 as a typical example. Here, thefocus detection devices are collectively referred to as a focusdetection device 116 ad as a seventh line sensor unit.

The focus detection device 116 ad includes five pixels pad1 to pad5. Thepixels pad1 to pad5 include photodiodes 1160 ad-1 to 1160 ad-5 and MOStransistors 231 to 235 and 236 to 240 respectively. The MOS transistors231 to 240 are provided to amplify a signal based on electrical chargegenerated from the photodiodes 1160 ad-1 to 1160 ad-5 and transfer theelectrical charge when the MOS transistors have an electrical chargetransfer structure. The MOS transistors 231 to 240 are exemplarilyshown. In FIG. 5D, reference numeral 2017 denotes the gate of the MOStransistor 231 and reference numeral 2018 denotes the main electroderegion of the MOS transistor 231. The focus detection device 116 ad 1 isdisposed away from the focus detection device 116 ad 2 used as an eighthline sensor unit and makes a pair with the focus detection device 116 ad2. The pixels included in the focus detection device 116 ad 2 arearranged along a fourth direction.

In the focus detection device 116 ad, the pixels pad1 to pad5 arearranged along a D direction. The channels of the MOS transistors 231 to235 are provided in the Y direction in FIG. 5D. Here, “the channel ofthe transistor is provided in the Y direction” means a configuration inwhich a channel region formed below the gate when the transistor isturned on causes a source region and a drain region located in the Ydirection to be electrically connected to each other. On the other hand,the channels of the MOS transistors 236 to 240 are provided in the Xdirection. In other words, when the Y direction is defined as the firstdirection, the X direction is defined as the second direction, and the Ddirection is defined as the fourth direction, the pixels pad1 to pad5are arranged in the fourth direction and the channels of the transistorsincluded in the pixels pad1 to pad5 are provided in the first or thesecond direction.

When generalizing the above description, the photoelectric conversionapparatus includes the first line sensor in which a plurality of pixelsare arranged along the first direction, the second line sensor in whicha plurality of pixels are arranged along the second direction, and thethird line sensor in which a plurality of pixels are arranged along thethird direction. The first direction and the second direction areperpendicular to each other. The third direction is a directiondifferent from the first and the second directions. The channels of thetransistors included in the first to the third line sensors are providedin the first or the second direction. When the photoelectric conversionapparatus further includes another line sensor, pixels included in theline sensor are arranged in the fourth direction different from thefirst to the third directions. The channels of the transistors includedin the line sensor are also provided in the first or the seconddirection.

“Directions of channels of two transistors are perpendicular to eachother” may be rephrased as “although two transistors are not in the sameplane direction with respect to a semiconductor substrate on which thetransistors are formed, the transistors are in plane directionsequivalent to each other”. It may be also represented that, when seeingtwo transistors from above, a direction of a tangent line of a side onwhich the gate electrode of one transistor is in contact with the sourceand the drain orthogonally intersects a direction of a tangent line of aside on which the gate electrode of the other transistor is in contactwith the source and the drain. For example, in FIG. 5A, a side on whichthe gate electrode 2011 of the transistor 201 is in contact with thesource and the drain is in the Y direction and a side on which the gateelectrode of the transistor 206 is in contact with the source and thedrain is in the X direction, so that the direction of the channel of thetransistor 201 and the direction of the channel of the transistor 206are perpendicular to each other.

The advantage of the configuration of the photoelectric conversionapparatus described above will be described. Generally, a MOS transistorformed on a semiconductor substrate varies its characteristics dependingon the direction of the channel. This is because a semiconductorsubstrate has plane directions and carrier mobility has a planedirection dependence. As a result, MOS transistors which are formed onthe same substrate and whose channel directions are different from eachother have different device characteristics. Generally, it is easy tocause two transistors whose channel directions are perpendicular to eachother to have characteristics corresponding to each other. This isbecause, in transistors formed so that the channel directions areperpendicular to each other, the channels are formed in plane directionsequivalent to each other.

On the other hand, it is difficult to cause a transistor whose channeldirection is diagonal to the directions perpendicular to each other tohave characteristics corresponding to the characteristics of thetransistors in which the channels are provided in the directionsperpendicular to each other due to the plane direction dependence of thecarrier mobility. Therefore, in the present embodiment, regardless ofthe direction in which the pixels are arranged, the channel of thetransistor included in each pixel is provided in the first or the seconddirection, so that the characteristics of the transistors may correspondto each other, and thus the accuracy of an obtained signal is improved.It is not necessary that channels of all the transistors included in thepixels are provided in the first direction, but, as shown in FIGS. 5A to5D, the transistors may include channels provided in the first directionand the second direction.

Although the X direction and the Y directions are perpendicular to eachother in the above description, for example, an error of about ±5degrees caused during a manufacturing process may be allowed.

In particular, for a transistor that forms a signal output path, such asan amplifier transistor and a pixel selection transistor, it isdesirable that the characteristics of the transistors correspond to eachother between the focus detection devices. It is desirable that at leastthe directions of the channels of amplifier transistors are the samebetween two focus detection devices that form a pair.

Second Embodiment

Another embodiment will be described. Differences from the firstembodiment will be mainly described.

FIG. 6 shows a unit pixel pix and a transfer portion connected to theunit pixel pix. The unit pixel pix corresponds to a pixel shown in thefirst embodiment. The unit pixel pix includes a sensor cell portion 1010and a first memory cell portion 301. In FIG. 6, “φX” given to a controlelectrode of a MOS transistor and a switch indicates a signal suppliedfrom a control unit not shown in FIG. 6.

In the unit pixel pix, the sensor cell portion 1010 includes aphotodiode (PD) 1160 which is a photoelectric converter, MOS transistors1110 to 1150, and a capacitance element (CP) 1070 which is a capacitanceportion. When the MOS transistor 1120 which is a pixel select portionbecomes conductive, the MOS transistor 1110 operates as a reverseamplifier whose gain is −1 along with the load MOS transistor 1130. TheMOS transistor 1110 is a pixel output portion that outputs a signalbased on an electric charge generated by the photoelectric converter.The control electrode of the MOS transistor 1110 functions as an inputterminal of the reverse amplifier and is connected to the anode of thePD 1160 and one main electrode of the MOS transistor 1150 which is asensitivity change switch. Thereby, the sensor cell portion 1010 mayoperate in a low sensitivity mode and a high sensitivity mode.Specifically, in the low sensitivity mode, the PD 1160 and the CP 1170are electrically connected to each other, and in the high sensitivitymode, the PD 1160 and the CP 1170 are electrically insulated from eachother. The other terminal of the MOS transistor 1150 is connected to oneterminal of the CP 1170 and one main electrode of the MOS transistor1140. The other main electrode of the MOS transistor 1140 is connectedto one terminal of the load MOS transistor 1130 and one terminal of theMOS transistor 1120. The other main electrode of the MOS transistor 1120is connected to one main electrode of the MOS transistor 1110. In such aconfiguration, when the sensor cell portion 1010 is in the highsensitive mode, the MOS transistor 1150 is in a non-conductive state anda parasitic capacitance Cpd of the PD 1160 determines the sensitivity ofthe sensor cell portion. On the other hand, when the sensor cell portion1010 is in the low sensitive mode, the MOS transistor 1150 which is aswitch portion becomes conductive by a signal φSW, so that thephotodiode 1160 and the capacitance element 1170 are connected inparallel with respect to a path from a power supply voltage VDD to GND.Therefore, a sum of the parasitic capacitance Cpd of the PD 1160 and acapacitance value CP of the capacitance element 1170 (Cdp+CP) determinesthe sensitivity of the sensor cell portion.

The MOS transistors 1140 and 1150 function as a write switch for writinga pixel portion reset noise when a residual electric charge of the PD1160 is reset by signals φPS1 and φSW.

The first memory cell portion 301 includes a memory capacitance 335 andMOS transistors 331 to 334. The first memory cell portion 301 has aconfiguration in which the photodiode 1160, the capacitance element1170, and the MOS transistor 1150 of the sensor cell portion 1010 arereplaced by the memory capacitance 335. Functions of the MOS transistors331 to 334 are the same as those of the MOS transistors of the sensorcell portion 1010.

A transfer portion 201 includes MOS transistors 221 to 224, a constantcurrent source 225, a transfer switch 226, a feedback switch 227, and atransfer capacitance 228. A signal held by each memory cell portion isoutputted from the reverse amplifier thereof, and when the transferswitch 226 is conductive and the MOS transistor 224 becomes conductiveby a signal φH inputted from a shift register not shown in FIG. 6, thesignal outputted from the reverse amplifier is transferred to a bufferamplifier 202.

A common output line 1020 is connected to one terminal of the transferswitch 226 and one terminal of the feedback switch 227. This node N4doubles as an input terminal and a first output terminal of the transferportion. The other terminal of the transfer switch 226 is connected toone main electrode of the MOS transistor 222, one main electrode of theMOS transistor 224, and one terminal of the transfer capacitance 228.The other main electrode of the MOS transistor 222 is connected to apower supply voltage VRS. The other main electrode of the MOS transistor224 is connected to the buffer amplifier 202 through a second outputterminal N5 of the transfer portion. The other terminal of the transfercapacitance 228 is connected to one main electrode of the MOS transistor223 and the control electrode of the MOS transistor 221. The other mainelectrode of the MOS transistor 223 is connected to a power supplyvoltage VGR. The power supply voltage VGR satisfies a relationship ofVGR=VRS+Vth when the threshold voltage of the MOS transistor 221 is Vth.The MOS transistor 221 and the constant current source 225 forms asource follower circuit and the output of the source follower circuit isconnected to the other terminal of the feedback switch 227. The outputterminal of the source follower circuit is also connected to a thirdoutput terminal N6 of the transfer portion 201 and the third outputterminal N6 is connected to a post-stage monitor portion.

The monitor portion monitors in real time a signal outputted from thetransfer portion while automatic gain control is being performed. Themonitor portion includes a variable gain amplifier, a maximum value andminimum value detector (Peak-Bottom detector; PB detector), a PKcomparator, and the like.

The PB detector shown in FIG. 7 includes a maximum value detectingcircuit 31 and a minimum value detecting circuit 32 and input terminals311, 312, and so on are connected to an output of each monitor portion.Here, regarding the maximum value detecting circuit 31 and the minimumvalue detecting circuit 32, a configuration for three unit pixels isextracted and shown. A signal inputted in an input terminal 311 isconnected to the non-inverting input of amplifiers 314 and 324. Thesource electrode of an NMOS transistor 341 whose control electrodereceives an output of the amplifier 314 is connected to the invertinginput of the amplifier 314. In the maximum value detecting circuit 31,when a switch becomes conductive by a signal 317, a plurality of NMOStransistors 341, 342, and so on and a common constant current sourceload 319 form a source follower. By this configuration, a maximum valueof a plurality of inputs to the maximum value detecting circuit 31 istransmitted to a maximum value and minimum value comparator (PEAK-BOTTOMcomparator; PB comparator) as a PEAK output 318.

On the other hand, although the minimum value detecting circuit 32 has asimilar configuration to that of the maximum value detecting circuit 31,the minimum value detecting circuit 32 is different from the maximumvalue detecting circuit 31 in a point that PMOS transistors 351, 352,and so on and a constant current source load 329 form a source follower.By this configuration, a minimum value of a plurality of inputs to theminimum value detecting circuit 32 is transmitted to the PB comparatoras a BOTTOM output 328.

FIG. 8 is a diagram showing a configuration example of the PBcomparator. The PB comparator obtains a differential signal between thePEAK output 318 and the BOTTOM output 328 of the PB detector shown inFIG. 7. In FIG. 8, an input terminal 413 is connected to the PEAK output318 and an input terminal 414 is connected to the BOTTOM output 328.Both input signals are supplied to a differential amplifier 411 and adifferential signal of the differential amplifier 411 is supplied fromthe output terminal of the differential amplifier 411 to the invertinginput terminal of a comparator 412. A low voltage VDAC 415 set by adigital-analog (DA) converter not shown in FIG. 8 is inputted in thenon-inverting input terminal of the comparator and the low voltage VDAC415 and the differential signal are compared. A result of thecomparison, that is, a contrast, is greater than or equal to a thresholdvalue, a control unit not shown in FIG. 8 ends an accumulation operationof the sensor cell portion 1010. For example, the value of the VDAC 415is varied such as 1.6 V, 0.8 V, 0.4 V, and 0.2 V corresponding to gainvalues ×5, ×10, ×20, and ×40 of the variable gain amplifier of themonitor portion.

FIG. 9 shows a layout of the sensor cell portion according to thepresent embodiment. Here, in the same manner as the focus detectiondevice shown in FIG. 5D, a state in which a plurality of pixels arearranged in the D direction is shown. Portions corresponding to portionsshown in FIG. 6 are enclosed by a dashed line and the same referencenumerals as those in FIG. 6 are given. However, the MOS transistor 1130is not shown.

The photoelectric conversion portion 1160 extends in a directionperpendicular to the D direction and the MOS transistors forming a partof the sensor cell portion are arranged below at right of thephotoelectric conversion portion 1160.

As shown in FIG. 9, the gate electrodes of the MOS transistors 1110,1120, 1140, and 1150 extend in the X direction in FIG. 9 and thechannels thereof are provided in the Y direction.

FIG. 10A is an enlarged view of transistors in one sensor cell portionof the configuration shown in FIG. 9. In FIG. 10A, the photoelectricconversion portion 1160 is connected to the gate electrode of the MOStransistor 1110 through wiring. The photoelectric conversion portion1160 and the gate electrode 1150G form the MOS transistor 1150.

The drain terminal of the MOS transistor 1150 and the source terminal ofthe MOS transistor 1140 share an impurity diffusion region. The impuritydiffusion region that forms the drain terminal of the MOS transistor1140 is connected to the common output line 1020. The impurity diffusionregion shared by the MOS transistors 1140 and 1150 is connected to thecapacitance 1170 through wiring.

An impurity diffusion region that forms the source terminal of the MOStransistor 1110 is connected to the power supply VDD through wiring andan impurity diffusion region that forms the drain terminal of the MOStransistor 1110 is connected to the MOS transistor 1120. The drainterminal of the MOS transistor 1110 and the source terminal of the MOStransistor 1120 share an impurity diffusion region.

The impurity diffusion region that forms the source terminal of the MOStransistor 1120 is connected to the common output line 1020.

FIG. 10B shows a cross-sectional view taken along line XB-XB in FIG.10A.

An N-type (first conductivity type) semiconductor substrate N-Sub has anN-type region NBL on the N-type semiconductor substrate NBL and furtherhas an epitaxially grown layer Epi on the N-type region NBL.

A P-type (second conductivity type) semiconductor region PSR is providedin the epitaxial layer Epi. The semiconductor region PSR and theepitaxial layer Epi form the photoelectric conversion portion 1160. Apositive electric charge, which is generated in the photoelectricconversion portion 1160 when the photoelectric conversion portion 1160receives light, is accumulated in the semiconductor region PSR. N-typesemiconductor regions NSR1 and NSR2 and a P-type semiconductor regionPSR2 are formed on the semiconductor region PSR so as to cover thesemiconductor region PSR. The semiconductor regions NSR1 and NSR2 areset to a fixed potential in a normal operation. The semiconductor regionPSR2 has an impurity concentration higher than that of the semiconductorregion PSR and includes a P-type semiconductor region PSR2′ having animpurity concentration higher than that of the semiconductor regionPSR2. The semiconductor region PSR2′ is connected to the gate electrodeof the transistor 111 through wiring including a plug P1.

Further, an N-type well region NWL is formed in the epitaxial layer Epi.The transistors 115 and 114 are formed on the N-type well region NWL. AP-type semiconductor region PSR3 and a P-type semiconductor region PSDare formed in the well region NWL. SiO2 is a silicon oxide film forseparating elements from each other.

The gate electrode 1150G is provided near the semiconductor regions PSR2and PSR3 and over the well region NWL with an insulting film in between.

The semiconductor region PSR3 is connected to the capacitance element1170 through a semiconductor region PSR3′ having an impurityconcentration higher than that of the semiconductor region PSR3 andwiring.

The gate electrode 1140G is provided near the semiconductor regions PSR3and PSD and over the well region NWL with an insulting film in between.

The semiconductor region PSD is connected to the common output line 1020through a semiconductor region PSD′ having an impurity concentrationhigher than that of the semiconductor region PSD and wiring.

Although FIG. 10 shows an example in which the photoelectric conversionportion 1160 and the MOS transistor 1150 are formed in the same activeregion, the photoelectric conversion portion 1160 and the MOS transistor1150 may be formed in active regions different from each other.

FIG. 10C shows a cross-sectional view taken along line XC-XC in FIG. 9.FIG. 10C shows the photoelectric conversion portion 1160 related tothree sensor cells adjacent to each other. As understood from FIG. 10C,the semiconductor region PSR formed in the epitaxial layer Epi islocated in only a part of the cross section taken along line XC-XC andsurrounded by the epitaxial layer Epi. The photoelectric conversionportions 1160 of adjacent pixels are separated by the well region NWLand the silicon oxide film SiO2.

A metal wire layer that forms the common output line 1020 is providedabove the silicon oxide film SiO2 with an insulating layer INS inbetween.

Next, in the same manner as the focus detection device shown in FIG. 5C,a layout of the sensor cell portion in which a plurality of pixels arearranged in the S direction will be described. FIG. 11 is a plan viewshowing a part of one sensor cell portion.

In the same manner as in the plan view of FIG. 10A, portionscorresponding to portions shown in FIG. 6 are enclosed by a dashed lineand the same reference numerals as those in FIG. 6 are given.

A configuration shown in FIG. 11 is obtained by rotating theconfiguration shown in FIG. 10A in a counterclockwise direction by 90degrees. In other words, while a plurality of sensor cell portions arearranged in the S direction (third direction) in FIG. 10A, a pluralityof sensor cell portions are arranged in the D direction (fourthdirection) in FIG. 11. Also, while the direction of the channels of thetransistors 1110, 1120, 1140, and 1150 is the Y direction (firstdirection) in FIG. 10A, the direction of the channels of the transistors1110, 1120, 1140, and 1150 is the X direction (second direction) in FIG.11.

Although not shown in the drawings, the focus detection devices shown inFIGS. 5A and 5B have a configuration similar to that shown in FIGS. 11and 10A. Specifically, in the focus detection device shown in FIG. 5A,the photoelectric conversion portion including the epitaxial layer Epiand the P-type semiconductor region PSR of the configuration shown inFIG. 11 extends in the X direction instead of the D direction. Also, inthe focus detection device shown in FIG. 5B, the photoelectricconversion portion including the epitaxial layer Epi and the P-typesemiconductor region PSR of the configuration shown in FIG. 10A extendsin the Y direction instead of the S direction.

As described above, in the photoelectric conversion apparatus includinga plurality of pixels arranged in the first direction, a plurality ofpixels arranged in the second direction, and a plurality of pixelsarranged in the third direction, the second direction is perpendicularto the first direction and the third direction is not perpendicular tothe first direction and the second direction. The channels of thetransistors included in the plurality of pixels arranged in the firstdirection, the plurality of pixels arranged in the second direction, andthe plurality of pixels arranged in the third direction are provided inthe first or the second direction. By this configuration, it is possibleto cause the characteristics of the transistors to correspond to eachother, so that the accuracy of the obtained signal is improved. It isnot necessary that channels of all the transistors included in thepixels are provided in the first direction, but, as shown in FIGS. 5A to5D, the transistors may include channels provided in the first directionand the second direction.

In particular, for a transistor that forms a signal output path, such asan amplifier transistor and a pixel selection transistor, it isdesirable that the characteristics of the transistors correspond to eachother between the focus detection devices. It is desirable that at leastthe directions of the channels of amplifier transistors are the samebetween two focus detection devices that form a pair.

The embodiments described above are only exemplifications for describingthe disclosure. The configurations of the embodiments may be changed andone embodiment may be combined with another embodiment without departingfrom the scope of the present invention.

While the disclosure has been described with reference to exemplaryembodiments, it is to be understood that the disclosure is not limitedto the disclosed exemplary embodiments. The scope of the followingclaims is to be accorded the broadest interpretation so as to encompassall such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2012-043963 filed Feb. 29, 2012, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A photoelectric conversion apparatus comprising:a first line sensor unit in which a plurality of pixels are arranged ina first direction; a second line sensor unit in which a plurality ofpixels are arranged in a second direction; and a third line sensor unitin which a plurality of pixels are arranged in a third direction,wherein each of the pixels includes a photoelectric conversion portionand a first transistor having a first channel in a first channeldirection, the second direction is perpendicular to the first direction,and the third direction is a direction different from the first and thesecond directions, and the first channel direction is in the firstdirection or the second direction regardless of whether the pixels arein the first, second, or third direction.
 2. The photoelectricconversion apparatus according to claim 1, wherein the third directionmakes an angle of 45 degrees with the first direction.
 3. Thephotoelectric conversion apparatus according to claim 1, wherein thepixel includes a pixel output portion that outputs a signal based on anelectric charge generated in the photoelectric conversion portion and apixel selection portion for selecting the pixel, and the transistor isat least one of the pixel output portion and the pixel selectionportion.
 4. The photoelectric conversion apparatus according to claim 1,wherein the pixel includes a capacitance portion and a switch portionthat connects the photoelectric conversion portion and the capacitanceportion.
 5. The photoelectric conversion apparatus according to claim 1,further comprising: a fourth line sensor unit in which a plurality ofpixels are arranged in the first direction and which is provided awayfrom the first line sensor unit in the first direction; a fifth linesensor unit in which a plurality of pixels are arranged in the seconddirection and which is provided away from the second line sensor unit inthe second direction; and a sixth line sensor unit in which a pluralityof pixels are arranged in the third direction and which is provided awayfrom the third line sensor unit in the third direction.
 6. Thephotoelectric conversion apparatus according to claim 1, furthercomprising: a seventh line sensor unit in which a plurality of pixelsare arranged in a fourth direction; and an eighth line sensor unit inwhich a plurality of pixels are arranged in the fourth direction andwhich is provided away from the seventh line sensor unit in the fourthdirection, wherein the fourth direction is a direction different fromthe first to the third directions.
 7. The photoelectric conversionapparatus according to claim 1, wherein each of the pixels furtherincludes a second transistor having a second channel in a second channeldirection, the first channel direction is in the first direction, andthe second channel direction is in the second direction, regardless ofwhether the pixels are in the first, second, or third direction.
 8. Thephotoelectric conversion apparatus according to claim 4, wherein theswitch portion includes the transistor.
 9. The photoelectric conversionapparatus according to claim 6, wherein the fourth direction isperpendicular to the third direction.
 10. A focus detection apparatuscomprising: the photoelectric conversion apparatus according claim 6,wherein the first and the fourth line sensor units form a pair, thesecond and the fifth line sensor units form a pair, the third and thesixth line sensor units form a pair, the seventh and the eighth linesensor units form a pair, and a focal point is detected by using atleast one of the pairs.
 11. An image pickup system comprising: the focusdetection apparatus according claim 10; an image pickup device includinga plurality of pixels arranged in a matrix pattern; and an opticalsystem which guides light from an object to the image pickup device andwhich divides the light guided to the image pickup device and guides thedivided light to the focus detection apparatus, wherein rows of thepixels of the image pickup device are arranged in the first direction,and columns of the pixels of the image pickup device are arranged in thesecond direction.
 12. A focus detection apparatus comprising: thephotoelectric conversion apparatus according claim 9, wherein the firstand the fourth line sensor units form a pair, the second and the fifthline sensor units form a pair, the third and the sixth line sensor unitsform a pair, the seventh and the eighth line sensor units form a pair,and a focal point is detected by using at least one of the pairs.
 13. Animage pickup system comprising: the focus detection apparatus accordingclaim 12; an image pickup device including a plurality of pixelsarranged in a matrix pattern; and an optical system which guides lightfrom an object to the image pickup device and which divides the lightguided to the image pickup device and guides the divided light to thefocus detection apparatus, wherein rows of the pixels of the imagepickup device are arranged in the first direction, and columns of thepixels of the image pickup device are arranged in the second direction.